A French drug banned in the U.S. offers a chemical end-runaround the running battle between pro- and anti-abortionAmericans.

RU486 is a progesterone-blocker that can prevent a freshlyfertilized egg from nesting in the uterus, and so terminate apregnancy before embryonic life begins.

Last January, the Clinton administration lifted a corner of theBush ban on RU486 by permitting its importation for researchpurposes, presumably prior to allowing its use as an early-stage alternative to abortion.

Also in January, at the University of Colorado Health SciencesCenter, pathologist Dean R. Edwards submitted a research paperto the Proceedings of the National Academy of Sciences (PNAS)titled "The progesterone antagonist RU486 acquires agonistactivity upon stimulation of cAMP signaling pathways." Thepaper appeared last Saturday in PNAS for mid-May.

In their report, Edwards and his colleagues reported amolecular paradox. While RU486 normally inactivatesprogesterone, when treated with cyclic AMP, the cells' "secondmessenger," RU486 can defect to the molecular enemy andactually stimulate tumor growth. Conceptually, it could converta breast-cancer patient's responsiveness to tamoxifen anti-estrogen therapy to resistance.

But not to worry.

As Edwards told BioWorld, "I don't want to overinterpret ourdata in cell culture, under the specific conditions that we lookat it." That is, RU486, in molecular tandem with cAMP,"exhibited substantial agonist activities with respect to theinduction of the progesterone-responsive mouse mammarytumor virus reporter gene in breast cancer cells."

Edwards explained that RU486, as presently used in Europe tocut short an early pregnancy, "is given very short-term. I thinkthat the clinical data for that usage show it's a very effectivecompound, and not a problem."

He would be more concerned, Edwards added, if the drug, ashas been suggested, were to be developed for long-termrepeated use as a contraceptive. -- David N. Leff051893RU486

(c) 1997 American Health Consultants. All rights reserved.

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